Tkinter doesn't support large integers

[serhiy-storchaka]

BPO	16840
Nosy	@loewis, @vstinner, @benjaminp, @serhiy-storchaka
Files	tkinter_bignum_4.patch tkinter_hexversion.patch

^{Note: these values reflect the state of the issue at the time it was migrated and might not reflect the current state.}

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GitHub fields:

assignee = 'https://github.com/serhiy-storchaka'
closed_at = <Date 2015-04-22.12:33:08.917>
created_at = <Date 2013-01-02.15:09:13.577>
labels = ['type-feature', 'expert-tkinter']
title = "Tkinter doesn't support large integers"
updated_at = <Date 2015-04-22.12:33:08.916>
user = 'https://github.com/serhiy-storchaka'

bugs.python.org fields:

activity = <Date 2015-04-22.12:33:08.916>
actor = 'serhiy.storchaka'
assignee = 'serhiy.storchaka'
closed = True
closed_date = <Date 2015-04-22.12:33:08.917>
closer = 'serhiy.storchaka'
components = ['Tkinter']
creation = <Date 2013-01-02.15:09:13.577>
creator = 'serhiy.storchaka'
dependencies = []
files = ['38198', '39158']
hgrepos = []
issue_num = 16840
keywords = ['patch', 'needs review']
message_count = 21.0
messages = ['178815', '178988', '179204', '195916', '218743', '235098', '236375', '236381', '236386', '236387', '239928', '239932', '240224', '240228', '240442', '241628', '241630', '241706', '241708', '241729', '241785']
nosy_count = 6.0
nosy_names = ['loewis', 'vstinner', 'benjamin.peterson', 'gpolo', 'python-dev', 'serhiy.storchaka']
pr_nums = []
priority = 'normal'
resolution = 'fixed'
stage = 'resolved'
status = 'closed'
superseder = None
type = 'enhancement'
url = 'https://bugs.python.org/issue16840'
versions = ['Python 2.7', 'Python 3.4', 'Python 3.5']

[serhiy-storchaka]

A long time Tcl got support first 64-bit integers, and then arbitrary size integers. Python also supports arbitrary size integers. However Tkinter supports only C long integers. For example, on 32-bit platform:

>>> import tkinter
>>> t = tkinter.Tk()
>>> t.tk.call('expr', 2**30)
1073741824
>>> t.tk.call('expr', 2**31)
<wideInt object at 0x9122518>
>>> t.tk.call('expr', 2**63)
<bignum object at 0x9126010>

Those <wideInt object> and <bignum object> are not usable from Python. Potentially this can cause errors in some rare circumstances.

I'm working on a patch, but was faced with a problem. Tcl provides functions for conversions between Bignum Tcl object and mp_int, but it does not provide all functions for conversions between mp_int and bytes sequence. Which is better, add libtommath library to CPython dependencies, or implement the missing functionality manually? Or may be use haxadecimal representation for conversions?

[serhiy-storchaka]

Here is a patch which adds support of "wideInt" and "bignum" Tcl types.

[serhiy-storchaka]

I reclassify this as enhancement until the real bug is not found.

[serhiy-storchaka]

Patch updated.

[serhiy-storchaka]

Patch synchronized with tip and fixed support of Tcl <8.5.

[serhiy-storchaka]

Here is test failure related to this issue:

http://buildbot.python.org/all/builders/AMD64%20Windows8%202.7/builds/156/steps/test/logs/stdio

test test_tk failed -- Traceback (most recent call last):
  File "D:\buildarea\2.7.bolen-windows8\build\lib\lib-tk\test\test_tkinter\test_widgets.py", line 91, in test_use
    wid = parent.winfo_id()
  File "D:\buildarea\2.7.bolen-windows8\build\lib\lib-tk\Tkinter.py", line 839, in winfo_id
    self.tk.call('winfo', 'id', self._w))
TclError: integer value too large to represent

[serhiy-storchaka]

Updated patch now supports wideInt if PY_LONG_LONG is not defined or is not equal to Tcl_WideInt. getint() also now supports big integers (currently it returns ambiguous result for values outside the range of C signed int).

As far as this issue causes random tests failures, may be it makes sense to apply the patch to maintained releases. On other hand, looks as this happens very rarely.

[benjaminp]

I'm all for fixing random test failures.